Patent GB-692727-A (GB)
Title: Improvements in or relating to engines having rotary cylinders
IPC: F02B57/06
Filed: 1950-11-03
Abstract: 692,727. Compressed-air engine. BROOM & WADE, Ltd., BROOM, H. S., and GITTINS, H. B. Oct. 23, 1951 [Nov. 3, 1950], No. 26956/50. Classes 122(ii), 122(iii) and 122(iv) In a rotary cylinder engine having a coaxial stationary gaseous-pressure fluid-distributing valve provided with admission and exhaust ports cooperating with ports in the engine cylinders and a separate throttle valve, the distributing valve is operatively connected with a fluid operated jack controlled by valves connected with the throttle valve and operable therewith by the throttle control member so that when the throttle is opened to admit working fluid to the distributing valve the jack control valves are automatically set for adjustment of the distributing valve to its correct position. The distributing valve 27 of a rotary cylinder compressed air engine comprises a stem 29 bored to form an exhaust passage 30 and a conical head 26 having admission and exhaust ports 32 and 31 respectively therein co-operating alternatively with ports 28 in the engine cylinders 16 and is operatively connected to a double-acting pneumatic jack 46 (Fig. 2) by a rack 48 on the jack piston 47 engaging teeth 49 on a quill 41 which surrounds the valve stem 29 and whose rotational movements are transmitted thereto by balls 43 engaging co-operating notches in the quill 41 and in an adjacent ring 34 secured by a grub screw 35 to the valve stem. Compressed air supply to the jack and the distributing valve is controlled by a rotary throttle valve operated by a lever 55 and comprising a disc 53 having six ports 57 therein and rotatable against a stationary seating 52 having therein four ports 58 leading to the distributing valve through a passage 59 and a chamber 33, and a further four ports 60-63 arranged in pairs on either side of the central vertical plane of the valve, one pair 60, 61 being connected by a duct 64 and a pipe 65 to one end of the jack 46 and the other pair 62, 63 being similarly connected by a duct 66 and a pipe 67 to the other end of the jack. Two of the ports 60, 62 can register with ports 57 when the disc 53 is rotated and the other two 61, 63 can register alternatively with a groove 68 in the face of the disc 53 leading to an exhaust port 69 in the seating 52. Compressed air is supplied to the throttle valve casing 50 by an inlet pipe 56 and when the throttle lever 55 is moved from its vertical position one of the ports 57 first comes into register with one or other of the ports 60, 62 to admit air to one end of the jack while at the same time the other end of the jack is exhausted through one of the ports 61, 63 and exhaust groove 68. The jack is thereby moved to one end of its stroke and adjusts the distributing valve to its correct running position. Further movement of the throttle lever 55 causes the ports 57 to overlap ports 58 to admit air to the engine cylinders and the engine speed is controlled by manipulation of the throttle lever; by moving the lever in the opposite direction past its vertical position the engine may be reversed. A coil spring 71 loosely surrounds the quill 41 with its arm 72, 73 resiliently bearing against two spaced stop pins 79 attached to the engine casing and the final movement of the distributing valve 27 in either direction is made against the spring resistance by a pin 76 on a flange 77 keyed to the quill bearing against one of the spring arms 72, 73. When the lever 55 is moved to full throttle position the port 57 supplying air to one end of the jack 46 moves out of register with the port 60 or 62 and one or other of two auxiliary exhaust grooves 78 cut in the face of the disc 53 and connected with the exhaust port 69 communicates with the port 61 or 63 connected to the said end of the jack so that both ends of the jack are open to exhaust and the distributing valve is then moved by the spring 71 in the opposite direction to its original rotation until the spring arm 72 or 73 contacts its stop pin 79, the port timing being thereby advanced. On movement of the lever 55 from full throttle position air is again admitted to the jack and the advanced port timing is nullified. The distributing valve may be arranged to automatically return to its neutral position due to the spring 71 when the throttle lever 55 is in its neutral position by replacing the two stop pins 79 by a single stop pin on the central vertical plane of the distributing valve or automatic advance at full throttle in one direction of engine running and automatic return to the neutral position in the other direction may be provided by having one stop pin 79 in the central vertical plane of the distributing valve and a second stop pin spaced therefrom. In a modification the throttle valve is spring loaded to return to its neutral position and also controls admission and exhaust of compressed air to a brake for the apparatus driven by the engine and the jack piston 47 is connected to the quill by a ball-andsocket joint. In a further modification the throttle valve comprises a hollow cone rotatable in a conical valve seat and the jack piston is returned to its central position by compression springs located in the jack cylinder. Specifications 571,319 and 611,575 are referred to.